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Thursday, January 08, 2015

Do we live in a computer simulation?

Some days I can almost get myself to believe that we live in a computer simulation, that all we see around us is a façade designed to mislead us. There would finally be a reason for all this, for the meaningless struggles, the injustice, for life, and death, and for Justin Bieber. There would even be a reason for dark matter and dark energy, though that reason might just be some alien’s bizarre sense of humor.
It seems perfectly possible to me to trick a conscious mind, at the level of that of humans, into believing a made-up reality. Ask the guy sitting on the sidewalk talking to the trash bin. Sure, we are presently far from creating artificial intelligence, but I do not see anything fundamental that stands in way of such creation. Let it be a thousand years or ten thousand years, eventually we’ll get there. And once you believe that it will one day be possible for us to build a supercomputer that hosts intelligent minds in a world whose laws of nature are our invention, you also have to ask yourself whether the laws of nature that we ourselves have found are somebody else’s invention.

If you just assume the simulation that we might live in has us perfectly fooled and we can never find out if there is any deeper level of reality, it becomes rather pointless to even think about it. In this case the belief in “somebody else” who has created our world and has the power to manipulate it at his or her will differs from belief in an omniscient god only by terminology. The relevant question though is whether it is possible to fool us entirely.

Nick Bostrum has a simulation argument that is neatly minimalistic, though he is guilty of using words that end on ism. He is saying basically that if there are many civilizations running simulations with many artificial intelligences, then you are more likely to be simulated than not. So either you live in a simulation, or our universe (multiverse, if you must) never goes on to produce many civilizations capable of running these simulations for one reason or the other. Pick your poison. I think I prefer the simulation.

Math-me has a general issue with these kinds of probability arguments (same as with the Doomsday argument) because they implicitly assume that the probability distribution of lives lived over time is uncorrelated, which is clearly not the case since our time-evolution is causal. But this is not what I want to get into today because there is something else about Bostrum’s argument that has been bugging Physics-me.

For his argument, Bostrum needs a way to estimate how much computing power is necessary to simulate something like the human mind perceiving something like the human environment. And in his estimate he assumes, crucially, that it is possible to significantly compress the information of our environment. Physics-me has been chewing on this point for some while. The relevant paragraphs are:

“If the environment is included in the simulation, this will require additional computing power – how much depends on the scope and granularity of the simulation. Simulating the entire universe down to the quantum level is obviously infeasible, unless radically new physics is discovered. But in order to get a realistic simulation of human experience, much less is needed – only whatever is required to ensure that the simulated humans, interacting in normal human ways with their simulated environment, don’t notice any irregularities. The microscopic structure of the inside of the Earth can be safely omitted. Distant astronomical objects can have highly compressed representations: verisimilitude need extend to the narrow band of properties that we can observe from our planet or solar system spacecraft. On the surface of Earth, macroscopic objects in inhabited areas may need to be continuously simulated, but microscopic phenomena could likely be filled in ad hoc. What you see through an electron microscope needs to look unsuspicious, but you usually have no way of confirming its coherence with unobserved parts of the microscopic world. Exceptions arise when we deliberately design systems to harness unobserved microscopic phenomena that operate in accordance with known principles to get results that we are able to independently verify. The paradigmatic case of this is a computer. The simulation may therefore need to include a continuous representation of computers down to the level of individual logic elements. This presents no problem, since our current computing power is negligible by posthuman standards.”

This assumption is immediately problematic because it isn’t as easy as saying that whenever a human wants to drill a hole into the Earth you quickly go and compute what he has to find there. You would have to track what all these simulated humans are doing to know whenever that becomes necessary. And then you’d have to make sure that this never leads to any inconsistencies. Or else, if it does, you’d have to remove the inconsistency, which will add even more computing power. To avoid the inconsistencies, you’ll have to carry on all results for all future measurements that humans could possibly make, the problem being you don’t know which measurements they will make because you haven’t yet done the simulation. Dizzy? Don’t leave, I’m not going to dwell on this.

The key observation that I want to pick on here is that there will be instances in which The Programmer really has to ramp up the resolution to avoid us from finding out we’re in a simulation. Let me refer to what we perceive as reality as level zero, and a possible reality of somebody running our simulation as level 1. There could be infinitely many levels in each direction, depending on how many simulators simulate simulations.

This idea that structures depend on the scale at which they are tested and that at low energies you’re not testing all that much detail is basically what effective field theories are all about. Indeed, as Bostrom asserts, for much of our daily life the single motion of each and every quark is unnecessary information, atoms or molecules are enough. This is all fine by Physics-me.

Then these humans they go and build the LHC and whenever the beams collide the simulation suddenly needs a considerably finer mesh, or else the humans will notice there is something funny with their laws of nature.

Now you might think of blasting the simulation by just demanding so much fine-structure information all at once that the computer running our simulation cannot deliver. In this case the LHC would serve to test the simulation hypothesis. But there is really no good reason why the LHC should just be the thing to reach whatever computation limit exists at level 1.

But there is a better way to test whether we live in a simulation: Build simulations ourselves, the more the better. The reason is that you can’t compress what is already maximally compressed. So if the level 1 computation wants to prevent us from finding out that we live in a simulation by creating simulations ourselves, they’ll have to ramp up computational efficiency for that part of our level 0 simulation that is going to inhabit our simulation at level -1.

Now we try to create simulations that will create a simulation will create a simulation and so on. Eventually, the level 1 simulation will not be able to deliver any more, regardless of how good their computer is, and the then lowest level will find some strange artifacts. Something that is clearly not compatible with the laws of nature they have found so far and believed to be correct. This breakdown gets read out by the computer one level above, and so on, until it reaches us and then whatever is the uppermost level (if there is one).

Unless you want to believe that I’m an exceptional anomaly in the multiverse, every reasonably intelligent species should have somebody who will come up with this sooner or later. Then they’ll set out to create simulations that will create a simulation. If one of their simulations doesn’t develop into the direction of creating more simulations, they’ll scrap it and try a different one because otherwise it’s not helpful to their end.

This leads to a situation much like Lee Smolin’s Cosmological Natural Selection in which black holes create new universes that create black holes create new universes and so on. The whole population of universes then is dominated by those universes that lead to the largest numbers of black holes - that have the most “offspring.” In Cosmological Natural Selection we are most likely to find ourselves in a universe that optimizes the number of black holes.

In the scenario I discussed above the reproduction doesn’t happen by black holes but by building computer simulations. In this case then anybody living in a simulation is most likely to be living in a simulation that will go on to create another simulation. Or, to look at this from a slightly different perspective, if you want our species to continue thriving and avoid that The Programmer pulls the plug, you better work on creating artificial intelligence because this is why we’re here. You asked what’s the purpose of life? There it is. You’re welcome.

This also means you could try to test the probability of the simulation hypothesis being correct by seeing whether our universe does indeed have the optimal conditions for the creation of computer simulations.

119 comments:

When you force the simulators to use more computing power, they have the option to comply, or they can mess with your world to make it harder for you to do this, or they could just turn off your simulation. So you risk killing everyone else in your simulation in your attempt to prove it is a simulation.

I've considered this, but all examples of 'messing to make it harder' I could come up with would only require more computing power. See, the simplest thing that you can do is set up some initial values and some time-evolution and just go. Every exception requires another program requires another criterion to be tracked and so on. The easiest way to convince conscious minds that their environment is consistent is if it is consistent.

(Besides: why would they want to do this? The very purpose of running the simulation is to create artificial intelligences who will ask for a higher resolution.) Best

Note that once you admit that it is possible that you are living in a simulation, you cannot say how probable this is, since any estimate will be based in the laws of nature in the simulation, whereas what is relevant are the laws of nature in the world in which the simulation is running.

I don't know what you mean with "all one really needs". All one really needs - for what?

Our technological achievements are a consequence of many of us living together. A single brain might be interesting for some reason or the other, but if you want rapid technological progress, you better do many. And since our universe is optimized for the creation of computer simulations, we know that we need at least 7 billion ;) Best,

Bostrom's (real name Boström; he's from Sweden)argument regarding the probability, as I mentioned above, implicitly assumes that the laws of nature in the simulation are the same as in the world in which it is running. OK, let's grant that for the minute. Then the conclusion is, we live in a simulation. But the same argument applies to the world in which the simulation is running. Does this lead to an infinite regress and, if so, is this a problem for the argument?

"I don't know what you mean with "all one really needs". All one really needs - for what?"

All that one needs to convince you that you are living in a simulated world. The only evidence you have of other people is via sensory input to your brain. So, if someone is simulating something, why go to the trouble of simulating all the other people, all the world, the universe---compressed or not? Just simulate your brain. Even if the simulator is interested in the interaction between simulated sentient beings, he still just has to simulate their brains and the sensory input---nothing else.

How do you know that I even exist? Your only evidence of me is through this comment box. :-)

"For his argument, Bostrum needs a way to estimate how much computing power is necessary to simulate something like the human mind perceiving something like the human environment."

Estimating how much computing power is necessary obviously depends on the laws of nature. Well, OK, the power itself doesn't, but estimating how difficult it is, how soon it will happen assuming Moore's law, etc, obviously depends on the technology, which depends on the laws of nature.

I agree with Bee. That we can't even calculate the energy levels of one single atom to the measured precision (except hydrogen or helium) makes me highly doubt that feasibility of a universal simulation. The degrees of freedom of even small quantum systems outnumber the particles in the universe. I believe one can possibly construct an argument such as "given a technology and a reasonable computing time, the computer needed to simulate a system with N degrees of freedom (this number includes the states it can assume as a result of time evolution) needs to be of a size (measured in terms of memory, benchmark speed or whatever) is larger than f(N) (where f is some very fast-growing function) (so that simulating a large universe requires an exponentitally larger computer). So I think real is real, simulated is imagined.

Follow-up: the most accurate and efficient simulator for, say, an electron is an actual electron. But then there is no point... So I guess we first need a definition of what is a "computer" and a "simulation". A computer should be able to simulate an electron or even a proton (but so far always to limited precision and detail), whereas a real electron can only simulate an electron, though in any detail.

Yes there is "extra" computation required to change simulated people's brains to reduce their interest in recursive simulations, but that could well pay off in reducing overall computation cost. Similarly, it takes more computation to notice if the simulated people are running physics experiments, so that you can clear up the crude approximations near their results. But that also can save overall.

The simulation hypothesis can be tested after we have a complete nonperturbative theory of quantum gravity. So far, via supergravity constructions, there exist configurations from D=11 that can be interpreted quantum computationally. However, given these intepretations, one is allowed LOCC, SLOCC and more general conformal and quasiconformal transformations on the states. So, even in an M-theory context, if our universe is indeed a large-scale quantum computation, it would not process information like a typical quantum computer.

I do not understand why a simulation must be done inside a computer.. You could also made an artificial enviromental. Lee Smoolin thesis is not so strange, after all. Secondly I suppose that once we will learned how to build the artificial intelligence we will discover that we've also learn how to build the 'artificial life' that, at the end will not be so different from us.So, much better to make some childs....

Yes it would bed hard to know you were in a simulation, if all you go on is the quality of the apparent outside world. Here's why I emphasize "outside": in the usual brain-in-a-vat idea, the brain (organic or itself a machine) is rather taken for granted "as is", with sensations fed in and motor signals acted upon for feedback etc. The Matrix follows this idea, just substituting a whole body for a brain.

Given that dichotomy, I (and presumably others) thought of a way to probably fool such simulations, if they don't work to simulate even the internal workings of the brain/equivalent to which the simulation is presented: try to commit suicide, take LSD etc and see what happens. If you try to shoot yourself in the head, the simulation will try to simulate a loud noise, painful penetration etc, but it can't simulate being indefinitely unconscious by simply withholding sensory input. Your brain will be aware it is at least there, thinking, have various spurious experiences from sensory deprivation etc. Nor can just mere "inputs" simulate the weird distortions of experience, time, identity etc. that are caused by some drugs (or even alcohol.) There are other examples, like trying to destroy a part of your brain controlling language comprehension: no manipulation of sensory inputs will keep you from understanding the meaning of words, or the manipulation will be noticeable as some distortion etc. that still isn't the same thing. And so on.

Has any one seen this "one weird trick" before, about how to fool simulations? It's rather macabre, but it should be effective in certain cases. However, a simulation might make you into a virtual machine in which case, those tricks wouldn't distinguish. But as I have argued, information processing isn't enough to simulate a genuine mind.

Heh, I just noticed that "brain hurting" remark - not the same idea as mine, but a cute coincidence. BTW also note that if you were in a simulation, you don't know how many other "people" are also real brains fed signals, or just constructs. It's solipsism all over again. (I get the impression that in The Matrix, other animals just weren't real.) And yeah, the Matrix had tools to get rid of you if you were supposed to die. But just destroying the brain of the person who "died" is easy compared with complex manipulations like my example of comprehension of language. And if something went wrong with your real brain instead (the flip side), the simulation needs to "write that into the script" to be credible: compare to actors dying etc. "Cheers."PS I guess it's clear I dig this kind of weird and troubling speculation.

Besides the shoddiness of the probability argument and the implausibility of simulating the level of detail—without introducing any glitches or inconsistencies, needed to evade our notice—I think there's the problem that no-one would have the motivation to actually carry out such a simulation. Would any civilization really want to devote the obscene amounts of resources necessary to build such a massive computer to simulate such pointless and uninteresting things as billions of ordinary people's daily lives and mental states in excruciating detail, and moreover be willing to hire a large enough staff to constantly be watching over everyone so that details can be ad hoc'd as necessary? The motivation behind such an endeavor is at least as implausible as the endeavor itself.

"The motivation behind such an endeavor is at least as implausible as the endeavor itself."

That might seem so to us, but consider the fact that many people spend appreciable fractions of their lives playing video games. In fact, it is no longer business (the "B" in "IBM") and no longer science which is driving technology advances in computing, but video games. A few years ago, video cards became so powerful that people started using them to do stuff which CPUs used to do. Yes, they can be used for many things, but the technology driver is video games.

BTW I figure that Bee is most essentially referring to full simulations in which "you" are part of the program and not a "brain" being fed sensations etc, but I wanted to note that little trick. Also, it's not clear that any program can simulate "you" - I myself do not agree with the AI thesis.

Of course maybe no program can simulate a physical universe like ours at all, anyway - if it exhibits genuine probabilism, trans-computable features etc. I know, RND generators, but consider the trouble of getting muon decay - each surviving cohort must act like a group that just came into existence. Etc.

"To avoid the inconsistencies, you’ll have to carry on all results for all future measurements that humans could possibly make, the problem being you don’t know which measurements they will make because you haven’t yet done the simulation."

If the horizon of the person doing the simulation doesn't extend indefintely far, then no, that's not necessary.

"Now you might think of blasting the simulation by just demanding so much fine-structure information all at once that the computer running our simulation cannot deliver. In this case the LHC would serve to test the simulation hypothesis."

Time-steps in the simulation do not have to bear a constant relationship to time outside the simulation. If more computational resources are required to simulate the LHC (or simulated us running a simulation one level down), then the outside experimented can just extend the time it takes to simulate one model timestep.

Sorry, Bee, I skimmed this post, not out of disrespect for your powers of analysis, which imo are considerable, but because everything I've ever learned from studying anthropology, psychology and philosophy tells me that this is not, and cannot ever be, cast as a problem of hard science, least of all physics. Or computer science for that matter. Especially not computer science.

The problem at hand has nothing to do with computers. The whole Matrix thing bothers me because it's not really about computers at all. It's about programming all right, but NOT computer programming. Because this sort of programming came into being long before computers.

We are all undoubtedly programmed, which means everything we "see," everything we "hear," everything we "think" is the result of conditioning since birth. Not by computers, but by our culture. It is culture that produces our reality, not computers. And as there are many different cultures, there are many different realities.

The notion that this is something new, or something having to do with modern science and technology is amusing. The Matrix is, on some level, a truly disturbing venture into the problem of human programming, which is very real. But the notion that this is something that could not have existed until computers came into existence is laughable, because the whole computer paranoia thing is part of our cultural programming to begin with.

Sometimes when you stare at something you can see through or beyond it as if you were near, or being near see deeply into an object or oneself. Our monitor is like an eternal eye of God over time and space we as mortals are suprised the back lit LED dust cancelles out the plasma shifts of gravity projected. Yet as immortal we can imagine something to survey and measure beyond our conceptual crutch of dark matter.

It is easier to mock up a "world" just for one single entity, than creating a world of entities who all "have" an equally complex unique self, and interact with each other. In a "singleton self" simulation all the others, the whole environmemt only needs to be made up of shallow masks, if you want like holograms one dimension "below".Do you have evidence, that there is more "reality" in the world than yourself? All you/we know (believe to know) stems from your/our perception, whatever this is.In my little world, "I" am writing this post to you (who maybe is just a shallow mask). In your little world, this post might just be an input from a shallow mask.

Be it simulation or not, "my" eigencomplexity will always be higher than that of "my" environment, as long as my very perception is the basis of that measurement.

In future years while some of these conclusions are true (after all our nerve connectionism seems physically holographic in density levels) the holographic principle by itself is primitive and incomplete.One can derive ten D geometry that does not depend on QM or string theory at all.

It is known, moreover, that circular reasoning and infinite regress can be valid analogies, especially in geometry as exactly true on some level.

But such thinking as cosmology goes back to the ancients by which we seem to be rediscovering as physics as part of the big picture. I did early on but used it as a playable 4D logical chess game. Back then I could not imagine the 5D game unless vaguely the field and pieces as universe played itself.

This feeling of being in a representation or simulation and necessary moments of doubt is universal to us all (humans anyway) and can be better resolved as physics between simulations (quasifinite or the discrete or continuous the open question.)

To those variations the linear view is just as important as information in the acid test of philosophy as free will or determinism (Sabines inquiry into physics as superdeterminism an essential step).

But I am not sure we can program all this into a simulation itself or if that thought would mean anything.

Current CPUs have 2 - 5 billion gates, GPUs 3 - 6 billion gates. A middling CPU has at least 2^(2 billion) states. Fill the world with computers (done!). The simulation blows big time if its components are constructed of atoms. Local space would be astronomically depleted of processor states.

http://www.universetoday.com/36302/atoms-in-the-universe/ The universe is conjectured to contain 10^82 atoms. That is piddles compared to the simulation of one CPU and its 10^(602 million) states.

If m is system mass (kg), R system radius (meters), and I contained information as the number of quantum state bits in the sphere, the Bekenstein bound is

I ~ 2.577×10^43(mR)

A human brain then has some 10^(7.8×10^41) states. It cannot be physically simulated. Quantum simulation cannot be constructed in time. Reality is not a simulation. Reality is theory with insufficient observation to constrain it, social activism to nullify cause and effect, and management to suffocate its evolution.

If the simulation is entanglement, dissipation is its minor death. A bound or entangled state has bookkeeping - binding energy. Visible mass would not work at scale.

Imposing a certain order on computation, temporal or atemporal, causal or casual, zero and successors, polynomial or deeper into arithmetic,or not. ; one simulated level program has been questioned early on until such ordering in a first few steps could guarentee that many steps away would not accumulate error. Thank you Intel.Can we as some say determine if a multiverse examining a single muon wobble. As Sagan suggested inside an electron is a whole universe and so on? Are we now sure a spinning star like a football can have two naked singularities? Do we program a computer to simulate particles so as to find the laws of nature or must we know those laws to program them?Is there really a minimum incompressible unit of information?If we meditate in (infinite) descent can by trying to quell our inner voice we reach that uncertain point a photon leaves the electron?Porn, virtual replication, drove the technology up to a certain threshold, then perhaps the gaming. But what is in the monolith if not the stars?If you find a shiver up your symmetry of spine that I programmed all this you now imagine, Earthlings, what will you do if I load the dice and walk away - perhaps think for yourself?

Whole the simulation thing is an apparent nonsense in the same way, like the mathematical universe thing. It's the product of simulation and mathematical thinking of people payed for doing of physics and it's ideologically just another version of creationism and postmodern religious belief in some deity. The appearance of Universe is apparently and massively emergent and its underlying nature is fully random.

Sure, I agree that you only need to simulate one brain to convince that brain it's in a simulation, and that I don't actually know my commenters exist has been a recurring joke on this blog, but this was probably before you joined. But look, you still have to simulate that what you feed the brain, and I don't see how that is any different from simulating the environment. In fact, to me it's the same exactly since I don't know you exist. Best,

Fizz: No, I didn't overlook this, I explicitly referred to it in my post, look again. It's where I talk about inconsistencies. You are overlooking something - you can't just 'edit' something out without knowing what and what to replace it with. This just adds difficulty. It's easier (less computational requirements) to just get it right the first time. Best,

Nemo: Yes, that's right. Computer is just some way of calling whatever it is that contains the simulation. Computer might or might not be a good word. It doesn't mean all that much. As has been observed previously, in some sense our universe is also a 'computer'. Best,

Jerry: I know this paper, and it's just a shady way of selling constraints on discretization that otherwise nobody would have been interested in. Do you really think it's plausible that the evidence for living in a computer simulation would be a *fixed* grid size? A *cubic* one in addition?? Best,

I think that if there were a super advanced race of people, they would he offspring with blank brains, like us. So, wouldn't it be much faster to download a moral, logical, and creative operating system for a blank brain? Christianity matrix style. The world is a test, I used to party a liked doing some drugs. Now I realize that I was just preoccupying my mind with something that doesn't matter. So now I know not to do that. As the future humans download this operating system into our brains we experience it. As the download increase from 0 to 100 percent I experience it down to a defined unit of measure (time in the way I perceive it)

Back to future humans. They have humans physically cultivated until the brain is developed enough to experience a life in the old days (present time), and get something out of it. Now the person with the download already completed has no flaws because they have experienced the flaws in a sense real to the one who received the download.

This has no less proof than any religion and is more creative than believe I rot in the ground after I die. Who knows what happens after death, I know what make me comfortable though.

The problem with the idea that our universe is a computer simulation is that it corresponds to a very complicated metaphysics. Namely, you have to assume that there is a computer in which our universe is run as a simulation, which creates further questions of how to define this computer, who is running it and who is observing the results (God?). Some time ago I proposed a temporal platonic metaphysics, see arxiv:0903.1800, where the notion of time evolution and a universe was defined in the platonic realm of ideas, which can be thought of as a generalization of Max Tegmark's Mathematical Universe, such that the time evolution and non-mathematical ideas are included.

I see some interesting reflections on the whole ontological problem, of the meaningfulness of this proposal (over and above whether we can "tell the difference.") If one is a "realist", then there is a truth of the matter about what is the actual ultimate real constituent. If one's experienced apparent world is different, or contrived instead of being naturally informed through sensory input as we imagine for ourselves, then one should be considered to be "in a simulation", whether that being can find out or not. Yeah, logical positivism, but what about realism?

BTW some philosophers think the meaning problem is a real barrier to even posing the question. Hilary Putnam wrote that we can't all be brains in a vat, since our worlds for things would have been formed in that environment and not be available for contrast (in effect, read up on it in Wikipedia etc.) To me, his "argument" just illustrates the weakness of ordinary language "analytic" philosophy.

A rationalist will use the logic of computation over top of empiricism every time?

The dispute between rationalism and empiricism concerns the extent to which we are dependent upon sense experience in our effort to gain knowledge. Rationalists claim that there are significant ways in which our concepts and knowledge are gained independently of sense experience. Empiricists claim that sense experience is the ultimate source of all our concepts and knowledge.Rationalism vs. Empiricism

Plato (and this is in *your* court ;-): yes, there is "how we can know" - but there is a conceptual ideal of "realism" - that there is a truth of the matter about the universe, regardless of whether we can find out (e.g., is it really infinite or not), or even if there is any"body" around to find out. Do you agree?

A technologically mature “posthuman” civilization would have enormous computing power. Based on this empirical fact, the simulation argument shows that at least one of the following propositions is true: (1) The fraction of human-level civilizations that reach a posthuman stage is very close to zero; (2) The fraction of posthuman civilizations that are interested in running ancestor-simulations is very close to zero; (3) The fraction of all people with our kind of experiences that are living in a simulation is very close to one.

If (1) is true, then we will almost certainly go extinct before reaching posthumanity. If (2) is true, then there must be a strong convergence among the courses of advanced civilizations so that virtually none contains any relatively wealthy individuals who desire to run ancestor-simulations and are free to do so. If (3) is true, then we almost certainly live in a simulation. In the dark forest of our current ignorance, it seems sensible to apportion one’s credence roughly evenly between (1), (2), and (3).

Unless we are now living in a simulation, our descendants will almost certainly never run an ancestor-simulation.

Plato: I am using "the matter" in the logical sense of a genuine reality about which there are facts, like for "material fact", not an ontological commitment to a specific ultimate constituent or way for things to be (ie, I'm implying MUH or idealism just might be true etc.)

BTW, I think it is debatable or "depends" whether beings in a simulation can create their own simulations. Those constructing the "true simulation" just under the top "real" level of things, are under no obligation (altho they could if they wanted) to directly support further simulations. However, if one is an AI hard-liner, then the ability of the simulees (good term?) to create functionally active processes themselves, will make those processes "conscious" in turn.

If the simulating computer of our world is resource scarce, what if we try to construct a quantum computer to apply Shor's algorithm? Do it for discrete logs or elliptic curve logs because they are uniformly hard. To pick a "hard" integer to factorize as a test, we pretty much have to come up with two large prime numbers first, and our simulator can just read off the prime numbers during generation, and then feed them into the output of the simulated quantum computer. But if we pick a random instance of a discrete log or an elliptic curve log, either Shor's algorithm would myseriously break down, or our simulator is at least partially a quantum computer on its own.

If we are indeed in a computer simulation, that might increase our prospects for living forever, without having to bet on iffy risky mind uploading, and the whole "live long enough to live forever" thingy. We can hope our simulators are keeping a transcript of our simulated brain memories, and saving the "soul" to be "resurrected" in a higher reality. However, this might not be guaranteed, and maybe we ought to "pray" to our simulators begging for salvation and hope they take pity on us so that we may have eternal life.

Or maybe we just ought to hedge our bets, and both hope that we're already in a simulation and will be saved and also aim to upload our minds. Or even triple hedge by also leaving a huge digital footprint in the hope that some future AI can reconstruct our lives from our digital footprints. After all, isn't it worth everything to strive to become conscious forever?

" that I don't actually know my commenters exist has been a recurring joke on this blog, but this was probably before you joined. But look, you still have to simulate that what you feed the brain, and I don't see how that is any different from simulating the environment. In fact, to me it's the same exactly since I don't know you exist."

I'm usually in Sweden, not far from Stockholm, once or twice a year. Maybe we should have lunch there. Or here, when you are back in Germany. As Ted Nugent said, if I can take a bite out of it, it's real, otherwise it doesn't exist.

The 7 points of the argument above can conceivably be false, the following covers the reasoning as to why they may not be true.

The ability to simulate: Conceivably computers could simulate human personalities, which is the basis for all research in artificial intelligence. The existence of a non-natural soul would destroy this assumption, but generally this is likely to be a very true point. This property only needs to apply in principle because the simulators do not necessarily have to be our future selves, so if the human race doesn't, in fact, develop artificial intelligence this can't discount the simulation hypothesis.

How to simulate: Even if a computer of silicon chips couldn't simulate a mind, a computer made of neurons identical to a brain could - and a computer of silicon chips simulating something identical to a brain certainly could. Emergent phenomena imply that consciousness can be independent of the medium it is made out of and is instead dependent on the patterns that medium creates; without begging dualism, the difference in output between a human brain and a perfectly identical computerised copy is zero.

Simulation of people and environment: Arguments against the assumptions begin here. By handwaving the hardware and energy requirements to achieve such a thing, you could make billions of personalities if you can simulate one successfully. However, this is making a vast assumption; would people even want to? Proponents of the simulation argument may suggest that saying "no" to this is making assumptions about a race of beings so powerful that we couldn't possibly second-guess them. But this works in both directions; how could we second-guess an unknowable race of transhuman beings to conclude that they would simulate people.

Computational power: Given Moore's Law, and past increases in computing power, it's sort of a no brainer that much more powerful computers could exist in the future. It doesn't automatically follow they will be powerful enough and energy efficient enough to simulate the billions of sentient beings and the supporting universe required to form a simulation. See computing complexity below.

Multiple simulations: Similar to the above, it is a non sequitur to assume that because something is possible that it will be done repeatedly. Humans do, of course, have a propensity to do things "just because", but there could be practical considerations as well as the question "why bother?". See motives below.More simulated entities than real entities: This is the point that the simulation argument rests on - that there are more simulated entities than real entities. Both motives and practicalities can conspire against this assumption. It can easily be impossible to simulate a universe and considered pointless to do so.

Concluding that we are a simulation: Conceptually it's possible that we are a simulation. But given the active evidence and unfalsifiability of the proposal it's equally possible that aliens are responsible for human civilization, or possible that both aliens and humans exist in a simulation, and that simulated aliens are responsible for our simulated civilization.Simulation Argument

Generalizing Tegmark, interesting idea that may fit clearly into the topic context.1. Assume the minimum information is zero in the sense of time or is absolutely flat in the sense of motionless space.2.We are pieces on a chess board. Occasionally we find ourselves in motion. Then we ask if we are in a simulation. Then our heads go under water again.

Your Bostrum quote ends with "This presents no problem, since our current computing power is negligible by posthuman standards."

I find that more "immediately problematic", to use your words, than the need for essentially unbounded computational power. We have no idea whether posthumans will even exist, despite the idea being fashionable at the moment.

I am not a working scientist or philosopher. I am, however, a working consumer of science, beyond the extent to which we of course all are; I read at least a couple of dozen papers per week.

The sort of thing I read in your pull-quote tends to reinforce my belief that Weinberg had it right back in 1993, when he wrote his "Against Philosophy" chapter (widely available on the Web) in _Dreams of a Final Theory_.

Alice, We cannot award the Nobel Philosophy prize to Mother Nature because She would have to share it with a mulitverse of so called peers.Even Freud in the end who did not see dreams as symbols looked to Moses outside known systems. Greg.Phil J. Source code Hamiltonian? One may as well ask God or Chronus -the weak force will not inherit the earth. Nor will it bury evil in this world where already we are post human. Only now we know enough that there can be no excuse.

@Greg and similar comments: right, it's hard to judge how plausible a simulation is because we don't know how closely our/my (sorry) apparent universe matches the properties of the level-0 boss-reality in which the simulation is done. However annoying or allegedly "meaningless" (IMHO a wrongly-framed accusation), Descartes was right about how hard it is to know one's "true status".

Uncle AI, thanks... I Googled the issues. I do not understand "referenced " to what? But it does raise all the fundamental debates since 1929 Quantum Relativity. Such as coincidences or anthropic concerns.I last saw this number in a display in the Morehead Planetarium but the display replaced by history of computers.I cannot make sense of 3) it seems to make my smart phone call somewhere.I doubt moonbeam would get a Nobel prize for such work these days as we see the dark side of the moon (Chandra) and its clumpy reflection on the surface of the wavy water. Is a proton immortal or as Dirac said gravity changes over time? Eddington only said the number of charges were exact, not any particular proton.So I see a paper suggesting our black galactic core is a wormhole., yesterday, if that is observable even as a simulation does it matter if we move thru it more than once in time it will collapse? In organic molecules a proton in two places at once is very rare yes?I have about had it with the net and all the unreadable models. All the increasing computer power and what do we do with it? CES2015 for a flat screen TV. So we are in a competing simulation of two operating systems at once. (That goes for spin on the news too, sorry I feel a little stressed out.)

Hi Sabine, I've been following your blog off and on for many years, and this is my favorite post yet out of your probably 1000+ posts.

I have come to the same conclusions as you on my own. Have you thought about Fermi Paradox in relation to this? If someone is doing a mass simulation looking for something interesting (say offspring) then maybe we are "it" and there is no need for any other intelligent life. That would explain Fermi.

With due respect to s great university and a great nation, I am sure the research is much further along than your proposals that contain true insightful steps. But conclusions of subjective stances are not grounded.While surveying this approach sees the 3+1 formalism in a matrix it does not decisively solve the problem from hidden variables, hamiltonians orthogonal discreteness and all that.I saw a science daily discussion on the Churn numbers today. Still, it took us long enough. Still, it is only a beginning.

Just trying to understand the philosophical context of the simulation argument better.

All the objects of human reason or inquiry may naturally be divided into two kinds, to wit, “Relations of Ideas,” and “Matters of Fact.” Of the first are the sciences of Geometry, Algebra, and Arithmetic, and, in short, every affirmation which is either intuitively or demonstratively certain. That the square of the hypotenuse is equal to the square of the two sides is a proposition which expresses a relation between these figures. That three times five is equal to half of thirty expresses a relation between these numbers. Propositions of this kind are discoverable by the mere operation of thought, without dependence on what is anywhere existent in the universe. Though there never were a circle or triangle in nature, the truths demonstrated by Euclid would forever retain their certainty and evidence. Matters of fact, which are the second objects of human reason, are not ascertained in the same manner, nor is our evidence of their truth, however great, of a like nature with the foregoing. The contrary of every matter of fact is still possible, because it can never imply a contradiction and is conceived by the mind with the same facility and distinctness as if ever so conformable to reality. (Hume 1748, Section IV, Part 1, p. 40)Rationalism vs. Empiricism, The Intuition/Deduction Thesis

inMatrix,I read your web page.I am interested in Russian scientific root words.We share a great deal of ideas in common so my mathematical recreations certainly could be mistaken as physics. Life is too short for this poet to worry about that.We all have so much to do, These are interesting and optimistic times to see some answers, the reward is in the knowing, individually, some part of it. The sorrow is the stars I will not see await. Good Inquiring to you!

if we live in a computer simulation I hope it would explain why there are generations of fermions ! We should get this if we quantize energy. Since Heisenberg says that Time is complementary to Energy, one wonders if it makes sense to quantize time as well, and if we did that, would it too produce an analog of generation structure. Keeping in mind that muons look like ordinary particles, maybe such generation structure would have an ordinary looking consequence question: if spin is the quantum analog of rotation, what is the quantum analog of boost, since it is not compact ?The problem with the Poincare group is that it does not recognize any Generation Structure even though muons and taus have nice energy momentum vectors. One might argue that it is incomplete and there should be more irreducible representations.

Bee, I have to say, (after thinking about it a long time), that this post and its specific question does not reflect very well on you. It really does not appear different to me than posing the question "does God decide things".

I think the main point of science is to discover deep seated answers to things so you can solve the most pressing problems both in science and more generally here on Earth. This question of yours suggests just throwing up our hands and agreeing it's all pointless. The human brain has this tendency to "squirm like a toad" when confronted with a hard truth and a lie that benefits oneself. My observation is that most people will go with the lie.

An example would be having a father or mother that you are a favorite of but treats a sibling of yours horribly, perhaps to the point of torture. Rather than upset the delicate balance that has evolved over time that benefits one, the vast majority of people won't say a bad word about the parent because of the benefits they accrue.

In general people are observed to do this in all situations, writ large. That is, even from the nation state viewpoint. Physics does it too. If you are not winning an argument people try to distract people by framing questions in just such a way as you have. Distraction is a prime way of distracting people from coming to good answers to things if the good answer will not benefit them, or even harm them. It happens at all levels of society from kindergarten to the deathbed, without people knowing they are even doing it. I think you are doing it here and it just distracts people from actually expending energy to find answers in physics. It does this by convincing people it is hopeless, just like the multiverse. It is not so much an intellectual error but a moral error, and that is why intelligent people have come to such ridiculous conclusions over the last three decades in physics. It isn't a physics problem, it's a moral problem.

Brian Whitworth has covered this subject somewhat; he calls it the Virtual Reality Hypothesis (http://arxiv.org/ftp/arxiv/papers/0801/0801.0337.pdf). There's also a really good FQXi essay that answers some of the pertinent questions, I think it's in the continuous or digital contest. I can't remember the guys name but it's a good essay . . .

Eric,let us say this post and comments are the only simulation we know. In fact if there are may as well question our host's choices of who is favored or chosen can we ask of a distant god who chose and simulated her?The difference in foundations as Uncle AI points out could be Hari Sheldon and some centered galactic origin in Asimov's sci fi or those who see it all as Sheldon Cooper sitcom. Think phenomenology. And think a little more.Joel has the right question. If we answer the question of origins we can relate spin as a generational effect. How is it that some black holes spin?Can our mathematics or programming simulate that?

Eric, simulation is a fair question to ask about because perceivers/info-processors (whatever we are) don't have firm framing and context knowledge, just "inputs." If you're a realist, then there is an answer to whether our apparent reality/ies correspond to the character of the real world that ultimately sustains and contains us. Maybe science or whatever can answer that question (like the question, "is the universe literally infinite?"), maybe it can't.

Otto,I wasn't referring to Joel's comment but to Bee's post. There seems little more to me in Bee's post than the anthropic principle, i.e. we are here because this simulation puts us here. Period. It's not good science. Rather, it's actually a distraction from good science, and it's meant to be. That is the point. And I that's so whether Bee consciously understands that or not.

What my comment referred to was that 95% of what we do and say just justifies what we already want to be true, usually for pretty petty reasons. We always underestimate the pettiness of much of humanity and ascribe laughably high motives to ourselves. This occurs just as much in science as anywhere else.

Neil,"If you're a realist, then there is an answer to whether our apparent reality/ies correspond to the character of the real world that ultimately sustains and contains us"

I completely agree with that. The computer simulation idea puts the kibash to that whole enquiry. (At least in my mind)It instead puts into existance some other entity outside the universe being in charge and creating the program. So to me its just another way of dressing up the old fairy tales in more respectable clothes. I just think Bee has seen the Matrix one time too many.

Eric: "The computer simulation idea puts the kibash to that whole enquiry. (At least in my mind) It instead puts into existance some other entity outside the universe being in charge and creating the program."No, it doesn't put anything "into" existence, outside "the universe" - it means that the perceptions you have of an apparent universe, are misleading. The universe doing the simulation, is the actual "real" universe, you just don't know that. Nor does it have anything to do with god or gods, etc. I think your confusion is part of the sad legacy of the deceptive ordinary language movement in philosophy, with the worst and most pitiable take on the problem being that offered by Hilary Putnam.

Neil,I don't think I'm confused. Adding an additional layer of abstraction like a computer simulation on top of the known laws of physics, incomplete as they are, just does not make sense to me. To me its just anthropomorphizing current culture and adding it lock, stock, and barrel onto what's already known without any compelling scientific reason. But hey, if it pleases everyone here to use that to explain what we still don't know, well fine.

Personally I think it's just another cultural fad from people who are too unsophisticated about their own psyches to recognize.

Eric, Define Psyche or better "their own Psyche. "That is the question asked above. " Is it a scientific question that you can read the mind of god then read nothing there. ?Are you a program yourself only that by intuition executes cold proof as superior to intuition?What sort of logic that frames Joel's question as science and not loading the jury lawyer like before a trial by peers? Is that ethical? Or perhaps in itself that a model of a world where open inquiry does not matter?It is worth it to assume you are real. Neil certainly strikes me as real. Bee transcends our narrow arguements.The joke, if we care, will be on us.If this page is all there is as a simulation then from an existentialist stance I have failed to learn from or teach something while they were here and there was still time before such authors deleted their comments from this play.But it seems human nature to need dust to stand on, or in this case the screen of light. Hope is eternal, and despair solves our neurosis as finality.And sometimes our results as science can only be replicated when three or more are together, like the lowly bacteria, asymmetry of time, and their circular reasoning. Not playing nice can only reflect on ourselves.

I think inadvertently you hit on exactly what I was getting at. When people don't like things as they are they usually do not take responsibility for those things. If human affairs leads to wars and economic unfairness there is no one to blame but ourselves. There is no "computer simulation", "all powerful god", "multiverse" etc that is causing it. All those things are in the mind of men and women to distract them from taking responsibility and improving things.

But you are misapprehending things if you are saying that I cannot criticize Bee for helping to continue that cycle. It isn't personal. She has a lot of influence and that's why I felt it was important to respond.

Eric,so what do you think of Nick Bostrum's philosophic post? Are you saying Bee has no right to review it or discuss how it may relate to math and physics? Did you read it? Are you suggesting talking about it is the same as endorsing it.?Felix Klein gave an alternative view to Pontclaire - circular reasoning that would be truly an imperfect picture with a proof or not.Why is there effective theory? Isms that a science question? Are your hairs numbered and not a sparrow falls? An omniscient god with finer eyes to micromanage counting everything? What sort of all powerful entity do you tell us offends you?The only influence she has is reasonable self doubts as honest science and the common sense power of some new ideas. This is rare in these times of the same old religious cult of promised transhumanism.

Sure she has a right to discuss it but to me that isn't the problem. It's the energy used and diverted from (what I consider) much more realistic theories. And to what end. If energy really is finite, as I believe, then energy put into these far fetched theories simply slows and diverts progress from things that actually are testable and observable. And to what end?

That's the point where the subconscious rears its ugly head. One can rationalize anything. Believe me. Germans, of all nationalities, should know that bitter lesson and keep it at the forefront of their consciousness. And I speak as someone who is German on my mothers side but who never lived there.

Alice Why do you spend so much time drawing lines and circles Winthrop sand? There's fields to be plowed and seeds to plant.

Bob I am counting all the grains if sand as if we could fill the globe to the furtherest stars.

Alice So you want your helpmate to do most of the work? How unfair. You bit the apple too that sent us to this Forbidden Planet.

Bob But we can build our own Paradise, find again a fountain of eternal life.

Alice Don't you know all is coincidence? My moon covers a thirtieth of your sun against the sky? Venus never quite closes her Pentagram year cycles. Your sun not perfectly one in 720 parts around the twelve houses.

Bob My cylinder of measure can only see when you dance briefly with Mercury on the horizon or I'd fi blind. We are dust, not what's beyond holes in a firey canopy. But I could use a break to drink and bathe in your hanging gardens.

According to Thomas Campbell we are living in a virtual reality and that reality as we know it is based on information and created from this information as any other virtual reality simulation on a computer. Of course the time reversal causality of photons inside the double slit experiments can be explained with superluminal (longitudinal) scalar waves of vacuum, which the photons interfere with.

Eric, you say: "Adding an additional layer of abstraction like a computer simulation on top of the known laws of physics, incomplete as they are, just does not make sense to me." - but no one is adding layers just out of fun or relative to the existing laws per se. The point is, it is possible that is what is happening to us. (Yes, bringing up the possibility, not the assertion it is the case any more than to assert it is not, nor must not be.) We don't have the right to assume that our experiences are straightforward, ironically such an assumption is itself a sort of "religious faith" - compare Descartes! I don't know why so many thinkers think that the universe owes them an easy or even easier living, with no paradoxes or problems of knowledge.

BTW, the idea of "simulation" is to be distinguished from natural analogs, holographic projections etc, since it implies a contrived feeding of signals to a perceiver or group of them, that is not the way their environment really is (cf brain in a vat.)

Furthermore, if we are in such circumstances then it's possible there is a way to find out - I already gave a rather macabre example as far as biologically-based simulations go. Suppose we did certain experiments and found some inadequacies compared to what we are confident a "real world" could provide? Then we might have to conclude that we are in a simulation. The very possibility of discovering we are in a simulation, makes "the idea" of it meaningful even if there are other cases, that could not be found out.

Nice pondering. Having read the posting, I wanted to comment, but I noticed my thought was expressed at comment #3 by P.Helbig. So much about it.

Sometimes I have pondered, that there is the Heisenberg´s uncertainty principle, why is there such a physical law, or phenomenon? Is that the level of detail where the simulation´s computing power ends, and they just put a random number instead of anything "sensible".

Eric, if you are the same Eric whose comments I have seen at other websites, I usually understand and respect what you write, but not in this case.

I will take you at your word that you are not confused and understand that Dr. Hossenfelder was not advocating for the simulation hypothesis but rather responding to it skeptically after explaining it. You yourself (if you are who I think you are) have many times reacted to other people's odd notions skeptically. This may well be a waste of time that could be used to feed the starving but on the other hand reading Dr. Hossenfeld's posts brightens the day of many a person such as myself. In any case telling another person what to write or not write about on their personal blog also takes time which could be spent much better otherwise.

The main point of my post was to question that the simulation hypothesis is as unscientific as you seem to believe it is. You seem to have missed that point. I agree with you that there are currently other, more interesting questions that physicists should work on, in fact do work on. I find it disingenuous that you apparently simply criticize me for sometimes thinking about topics outside my current research.

If you don't think it's an interesting topic, well, nobody forced you to read it.

It's not necessarily true that the Virtual Reality Hypothesis posits some external creator; this is the old argument between the Buddhists and the Hindus, the Hindu posit some absolute creator, Brahman, while the Buddha said there is no such thing that it is all "self-generating," the ultimate nature of all existence is emptiness.

That said, I think this subject merits considerable attention due to reasons posited by Brian Whitworth and others (such as Hugo De Garis with his, "Is God an Alien Mathematician," essay: http://www.kurzweilai.net/from-cosmism-to-deism).

What's immoral in science is the tendency to ignore or blacklist possible explanations which don't necessarily conform to the standard dogma. But this is already a tired subject . . . And the Virtual Reality Hypothesis does not in any way eliminate morality, rather, it leads to a more holistic morality often referred to as De Garis' cosmism.

With regards to your comments, Eric, I would suggest that you are just shooting from the hip, governed by emotion rather than reason. Clearly, YOU have not invested much time nor energy in researching the subject. Your comments are rather shallow - no ill-will intended . . .

You write "I do not see anything fundamental that stands in way of such creation. Let it be a thousand years or ten thousand years, eventually we’ll get there."

Though I liked your following arguments, I disagree with the first because I do see something fundamental that blocks our way toward simulating a conscious mind.

A conscious mind at the level of that of humans, experiences sensations such as colors, tastes, smells, sounds, pains, pleasures. In the next level of a made-up reality (i.e. in the computerized simulation of humans' conscious minds), these sensations are represented by codes, sequences of ones and zeros in nowadays computerized systems (as graphically ornaments this present post..) that correspond to colors, tastes, smells, sounds etc. Since the connection between the code and the simulated feeling is in the conscious mind of the programmer, the simulation lacks a subjective meaning, i.e. it has no self conscious, at least not one that the programmer can be aware of. For a sensation to be real at the level of the simulated mind, the code and the sensation must be linked (or must be one and the same) in the level of the simulated system itself, regardless of the linkage between them in the programmer's level of reality.

This seems impossible to come up with (i.e. to remain with a code at the programmer's level, e.g. a sequence 00101011101 the meaning of which is a yellow color, and to somehow expect that the simulated mind will experience a yellow color, rather than a headache, let say, whenever 00101011101 pops up in one of the registers of the computerized system).

To summarize my point, let it be a thousand years or ten thousand years we will finally get there to make a simulation perfect in terms of its meaning to the programmer, but it will remain totally imperfect in terms of its meaning to the simulated conscious objects themselves.

Since our conscious minds experience a somewhat logical reality, and sensations that probably can never be transferred into a simulation in a manner assuring that the simulated conscious minds will experience what we, as programmers aiming to fool them, expect them to, our conscious minds at level 0 can rest assured that they are not being fooled by a programmer at level 1.

As a computer scientist, I find this assumption completly ridiculous if it is not only used to demonstrate that it is impossible to distinguish between a Turing equivalent universe and a not-Turing equivalent universe and therefore the only valid scientific position is to assert that the universe is Turing equivalent. It is time for physicists to understand that logic is purely transcendental contrary to the laws of physics that are immanents.

It is also time to replace the Schrödinger's cat by a formally deterministic system as a computer running a program. The only logical consequence is that the multiple universe theory of Everett becomes absolutely untenable because in all possible worlds, the deterministic system is determined.

I love this paper http://arxiv.org/pdf/0801.0337.pdf on The Physical World As A Virtual Reality from Brian Withworth, already in 2007. Great read and touching many subjects. It al started with someone hitting !

I believe the earth is the computer that projects the simulations,any thing that grows is loading in real time untill complete and recieves energy via wireless by harnessing the energy of the sun or some other energy source yet unknown. forget 8 core we run on earth core lol.

Many scholars in recent years have been trying to explain the behavior of Christ' disciples. Fully accepted now is that the disciples did believe they saw Jesus alive, which in turn is the only way to explain their diabolical message of loving you enemies and eventually allowing them to torture and kill them-all the while never denying that Christ was exactly who he claimed to be.

The dilemma for simulation is it easily explains his miracles as real as well as his resurrection, and thus a preplanned computer sim'd afterlife.

C Sim is the last ditch effort of the deniers of reality. It proves multiverse inept as it we'd all be sims and at the same time proves itself inept. It answers nothing, destroys the very results that led to its idea-which amazingly none of its proponents recognize, and it kicks the can down the street...dodging the obvious-where the original people and reality come from?

Its the ultimate self deception and the definition of lunacy. If the only way to escape what is plain is to pretend we're not real maybe another analysis of the real world and what history and the results of fine tuning are clearly showing mankund are in order

Computer has more influence in our life and now we cannot live and survive without it. I agree with your statement "If you just assume the simulation that we might live in has us perfectly fooled and we can never find out if there is any deeper level of reality, it becomes rather pointless to even think about it."

I must have repeated this several dozen times by now: this paper doesn't test whether we live in a simulation, it tests for Lorentz-invariance simulation. If The Programmer isn't smart enough to code for Lorentz-invariance, then, yes, this tests whether we live in a simulation. But that's quite a stretch. Best,

Is there any way for the person in simulation level L to tell whether or not the people who are simulating them from level L+1 are running them with some amount of slowdown? That is to say, can computation limits be mitigated by just slowing down the render speed for the simulated level below them? It seems to me that in this case as computational demand goes to infinity, time stops for the simulated universe. This is effectively like pulling the plug I suppose, but then it's an asymptotic thing.

Having worked in the area of computer simulations (used for training systems), I can't help feeling that really wonder whether these discussions are sustained through collective narcissism and delusion as to how crude human computer simulations really are.Perhaps we need to acknowledge the pitfalls of becoming preoccupied with a question that leads to an 'number of angels on a pinhead' kind of argument.

Friendly Neighborhood Copy Edit: In two places you say "cramp up" when you mean "ramp up" (the latter is the English expression for "significantly increase").

Also, "scrape it", at least in America, is "scrap it". (leftover pieces of metal were called "scrap", and thrown on a pile to be melted down and recast). But I notice several non-Americans saying "scrape it", which I guess retains the same sense of tossing it on a garbage heap.

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